Maleimide-based copolymer, method for producing same, and resin composition obtained using same

ABSTRACT

The present invention provides a maleimide-based copolymer, a method for producing same, and a resin composition obtained using same. 
     This maleimide-based copolymer contains 40-60 mass % of aromatic vinyl monomer units, 5-20 mass % of vinyl cyanide monomer units, and 35-50 mass % of maleimide monomer units, and is such that a 4 mass % tetrahydrofuran solution of the copolymer has a transmittance of 90% or more for light having a wavelength of 450 nm at an optical path length of 10 mm, and the residual maleimide-based monomer amount is less than 300 ppm. This maleimide-based copolymer preferably further contains 0-10 mass % of unsaturated dicarboxylic acid anhydride monomer units, and preferably has a glass transition temperature of 165° C. or higher.

TECHNICAL FIELD

The present invention relates to a maleimide-based copolymer, a methodfor producing the same, and a resin composition using the same.

BACKGROUND ART

An acrylonitrile-butadiene-styrene copolymer resin (ABS resin) is widelyused in automobiles, home appliances, OA equipment, home buildingmaterials, daily necessities and the like by utilizing its excellentmechanical strength, appearance, chemical resistance, moldability andthe like. For applications requiring heat resistance, such as interiormaterials for automobiles, an ABS resin containing maleimide-basedcopolymers is also used as a heat resistance imparting material (see,for example, Patent Documents 1 and 2).

The ABS resin containing the maleimide-based copolymers has adisadvantage in that it has poor chemical resistance. In order to solvethe disadvantage, a copolymer obtained by copolymerizing vinyl cyanidemonomers with the maleimide-based copolymers has been proposed (see, forexample, Patent Documents 3 and 4). The maleimide-based copolymerobtained by copolymerizing with the vinyl cyanide monomers has adisadvantage in that it tends to have yellow hue, poor natural colorappearance and poor colorability.

PRIOR ART DOCUMENTS

Patent Document 1: JPH57-098536A

Patent Document 2: JPH57-125242A

Patent Document 3: JP2004-339280A

Patent Document 4: JP2007-009228A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present invention provides a maleimide-based copolymer capable ofobtaining a resin composition having an excellent balance of hue,chemical resistance, heat resistance, impact resistance and fluidity,and a method for producing the same. The present invention also providesa resin composition having an excellent balance of physical propertiessuch as the hue, chemical resistance, heat resistance, impact resistanceand fluidity, obtained by mixing a maleimide-based copolymer with one ormore resins selected from a ABS resin, anacrylonitrile-styrene-acrylate-based rubber copolymer resin (ASA resin),an acrylonitrile-ethylene propylene-based rubber-styrene copolymer resin(AES resin) and a styrene-acrylonitrile copolymer resin (SAN resin).

Means for Solving the Problems

That is, the present invention is summarized as follows.

(1) A maleimide-based copolymer including 40 to 60% by mass of anaromatic vinyl monomer units, 5 to 20% by mass of vinyl cyanide monomerunits, and 35 to 50% by mass of maleimide-based monomer units, where atetrahydrofuran solution containing 4% by mass of the copolymers has atransmittance of 90% or more for light having a wavelength of 450 nm atan optical path length of 10 mm, and an amount of the residualmaleimide-based monomers is less than 300 ppm.(2) The maleimide-based copolymer according to (1), further including 0to 10% by mass of unsaturated dicarboxylic anhydride monomer units inthe maleimide-based copolymer.(3) The maleimide-based copolymer according to (1) or (2), having aglass transition temperature of 165° C. or higher.(4) A method for producing the maleimide-based copolymer according toany one of (1) to (3), including an initial polymerization step, amiddle polymerization step, a final polymerization step and animidization step,

where in the an initial polymerization step, a total amount of vinylcyanide monomers to be added, 10 to 90% by mass of a total amount ofaromatic vinyl monomers to be added, and 0 to 30% by mass of a totalamount of unsaturated dicarboxylic anhydride monomers to be added aremixed to start copolymerization,

in the middle polymerization step, 50 to 90% by mass of the remainingamount of the aromatic vinyl monomers used in the initial polymerizationstep and the remaining amount of the unsaturated dicarboxylic anhydridemonomers used in the initial polymerization step are each separately orcontinuously added to the mixture to continue the copolymerization,

in the final polymerization step, the remaining amount of the aromaticvinyl monomers used in the initial polymerization step and the middlepolymerization step is added to the mixture to obtain aromaticvinyl-vinyl cyanide-unsaturated dicarboxylic anhydride copolymers, and

in the imidization step, the obtained aromatic vinyl-vinylcyanide-unsaturated dicarboxylic anhydride copolymers are imidized withammonia or primary amine to obtain the maleimide-based copolymers.

(5) A resin composition including 5 to 40% by mass of themaleimide-based copolymers according to any one of (1) to (3), and 60 to95% by mass of one or more resins selected from an ABS resin, an ASAresin, an AES resin and a SAN resin.(6) An injection molded article using the resin composition according to(5).(7) The injection molded article according to (6), used as an interiormember or an exterior member of an automobile.

Effects of the Invention

The present invention provides the maleimide-based copolymer capable ofobtaining the resin composition having the excellent balance of the hue,chemical resistance, heat resistance, impact resistance and fluidity,and the method for producing the same. The present invention alsoprovides the resin composition having the excellent balance of thephysical properties such as the hue, chemical resistance, heatresistance, impact resistance and fluidity, obtained by mixing themaleimide-based copolymers with one or more resins selected from the ABSresin, ASA resin, AES resin and SAN resin.

DETAILED DESCRIPTION OF THE INVENTION Explanation of Terms

In the present application, the expression “A to B” means A or more andB or less.

The maleimide-based copolymer of the present invention can be obtainedby copolymerizing aromatic vinyl monomers, vinyl cyanide monomers andmaleimide monomers.

The aromatic vinyl monomer used for obtaining the maleimide-basedcopolymer is for improving hue of a resin composition obtained by mixingwith the maleimide-based copolymers. The aromatic vinyl monomer includesstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene, α-methylstyrene,and α-methyl-p-methylstyrene. Among them, the styrene is preferredbecause of its higher effect of improving the hue. Only one type of thestyrene-based monomers may be used, or two or more types of thestyrene-based monomers may be used in combination.

An amount of aromatic vinyl monomer units contained in themaleimide-based copolymer is 40 to 60% by mass, preferably 45 to 55% bymass. If the amount of the aromatic vinyl monomer units is less than 40%by mass, the resin composition has a yellow hue, and if it is more than60% by mass, the heat resistance of the resin composition decreases.

The vinyl cyanide monomer used for obtaining the maleimide-basedcopolymers is for improving chemical resistance of the resincomposition. The vinyl cyanide monomer includes acrylonitrile,methacrylonitrile, ethacrylonitrile, fumaronitrile. Among them, theacrylonitrile is preferred because of its higher effect of improving thechemical resistance. Only one type of the acrylonitrile-based monomersmay be used, or two or more types of the acrylonitrile-based monomersmay be used in combination.

An amount of vinyl cyanide monomer units contained in themaleimide-based copolymer is from 5 to 20% by mass, preferably from 7 to15% by mass. If the amount of the vinyl cyanide monomer units is lessthan 5% by mass, the effect of improving the chemical resistance of theresin composition cannot be exhibited, and if it is more than 20% bymass, the resin composition has a yellow hue.

The maleimide monomer used for obtaining the maleimide-based copolymersis used for improving the heat resistance of the resin composition. Themaleimide monomer includes N-alkylmaleimide such as N-methylmaleimide,N-butylmaleimide and N-cyclohexylmaleimide, N-phenylmaleimide,N-chlorophenylmaleimide, N-methylphenylmaleimide,N-methoxyphenylmaleimide, and N-tribromophenylmaleimide. Among them, theN-phenylmaleimide is preferable because of its higher effect ofimproving the heat resistance. Only one type of the maleimide monomersmay be used, two or more type of the maleimide monomers may be used incombination.

An amount of maleimide monomer units contained in the maleimide-basedcopolymer is 35 to 50% by mass, preferably 37 to 45% by mass. If theamount of the maleimide monomer units is less than 35% by mass, theeffect of improving the heat resistance of the resin composition cannotbe exhibited, and if it is more than 50% by mass, the impact strength ofthe resin composition decreases. The content of each monomer unitcontained in the maleimide-based copolymer is a value measured by C-13NMR method under the following measurement conditions.

Apparatus name: FT-NMR AVANCE300 (manufactured by BRUKER)

Solvent: Deuterated chloroform

Concentration: 14% by mass

Temperature: 25° C.

Number of scans: 10000 times

A tetrahydrofuran solution containing 4% by mass of the copolymer has atransmittance of 90% or more for light having a wavelength of 450 nm atan optical path length of 10 mm. If the transmittance is less than 90%,the hue of the resin composition obtained by mixing with one or moreresins selected from the ABS resin, ASA resin, AES resin and SAN resindeteriorates. The transmittance is preferably 92% or more. Thetransmittance is a value obtained by measuring a solution adjusted to 4%by mass of the maleimide-based copolymer in the tetrahydrofuran in thequartz square cell having a measurement optical path length of 10 mm,using a spectrophotometer V-670ST (manufactured by JASCO Corporation).

The amount of the residual maleimide-based monomers contained in themaleimide-based copolymer is less than 300 ppm, preferably less than 200ppm. If the amount of the residual maleimide-based monomers is 300 ppmor more, the obtained maleimide-based copolymer has a yellow hue. Theamount of the residual maleimide-based monomers is a value measuredunder the following conditions.

Apparatus name: Gas Chromatograph GC-2010 (manufactured by ShimadzuCorporation)

Column: Capillary column DB-5 ms (manufactured by Agilent TechnologyCo., Ltd.)

Temperature: Inlet temperature of 280° C., detector temperature of 280°C.

-   -   Perform a temperature rise analysis at a column temperature of        80° C. (initial).

(Temperature rising analysis conditions) 80° C.: constant for 12 minutes

-   -   80-280° C.: 10 min at 20° C./min    -   280° C.: constant for 10 minutes

Detector: FID

Procedure: 0.5 g of a sample is dissolved in 5 ml of a1,2-dichloroethane solution (0.014 g/L) containing undecane (internalstandard). Thereafter, 5 ml of n-hexane is added and shaken for 10 to 15minutes with a shaker to precipitate polymers. With the polymersprecipitated, only the supernatant is injected into the gaschromatograph. A quantitative value is calculated from the peak area ofthe obtained maleimide-based monomers using a coefficient obtained froman internal standard substance.

The maleimide-based copolymer may be copolymerized with acopolymerizable monomer other than the aromatic vinyl monomer, vinylcyanide monomer and maleimide monomer as long as the effects of thepresent invention are not impaired. The monomer copolymerizable with themaleimide-based copolymer includes an unsaturated dicarboxylic anhydridemonomer such as maleic anhydride, itaconic anhydride, citraconicanhydride and aconitic anhydride; an acrylate monomer such as methylacrylate, ethyl acrylate and butyl acrylate; a methacrylate monomer suchas methyl methacrylate and ethyl methacrylate; a vinyl carboxylicmonomer such as acrylic acid and methacrylic acid; acrylic amide; andmethacrylic amide. Only one type of the monomers copolymerizable withthe maleimide-based copolymer may be used, or two or more types of themonomers copolymerizable with the maleimide-based copolymer may be usedin combination.

The unsaturated dicarboxylic anhydride monomer is preferable as themonomer copolymerizable with the maleimide-based copolymer. If thecontent of the unsaturated dicarboxylic acid units is 0.5% by mass ormore, the unsaturated dicarboxylic acid unit is preferable because itreacts with resins having an amino group or alcohol group terminal toexhibit an effect as a compatibilizer. If the content of the unsaturateddicarboxylic anhydride monomer units is 10% by mass or less, it ispreferable because the thermal stability is excellent. If the content ofthe unsaturated dicarboxylic anhydride monomer unit is 5% by mass orless, it is more preferable because the thermal stability is moreexcellent.

The glass transition temperature of the maleimide-based copolymer ispreferably 165° C. to 200° C., more preferably 170° C. to 200° C., inorder to efficiently improve the heat resistance of the resin to bemixed such the ABS resin and ASA resin. The glass transition temperaturerefers to an extrapolated glass transition initiation temperature (Tig)of the maleimide-based copolymer measured by the following apparatus andmeasurement conditions in accordance with JIS K-7121.

Apparatus name: Differential scanning calorimeter Robot DSC6200(manufactured by Seiko Instruments Inc.)

Temperature rising rate: 10° C./min

In order to increase the glass transition temperature of themaleimide-based copolymer, the content of the maleimide monomer unitsmay be increased, or it may be copolymerized with a monomer having ahigher glass transition temperature.

Examples of the polymerization mode of the maleimide-based copolymerinclude solution polymerization and bulk polymerization. The solutionpolymerization is preferred from the viewpoint that a maleimide-basedcopolymer having a uniform copolymer composition can be obtained byperforming polymerization while separately or continuously addingmonomers to be copolymerized. The solvent for the solutionpolymerization is preferably non-polymerizable from the viewpoint thatby-products are unlikely to be formed and the adverse effects are small.The solvent includes ketone such as acetone, methyl ethyl ketone, methylisobutyl ketone and acetophenone; ether such as tetrahydrofuran and1,4-dioxane; aromatic hydrocarbon such as benzene, toluene, xylene andchlorobenzene; N, N-dimethylformamide; dimethylsulfoxide;N-methyl-2-pyrrolidone. Methyl ethyl ketone and methyl isobutyl ketoneare preferred from the viewpoint that the solvent can be easily removedduring devolatilization and recovery of the maleimide-based copolymers.Any of a continuous polymerization system, a batch system (batchsystem), and a semi-batch system can be applied to the polymerizationprocess.

A method for polymerizing the maleimide-based copolymer is preferably amethod for obtaining the copolymer by radical polymerization, where thepolymerization temperature is preferably in the range of 80 to 150° C.,but not particularly limited thereto. A polymerization initiator to beused can include a well-known azo compound such asazobisisobutyronitrile, azobiscyclohexanecarbonitrile,azobismethylpropionitrile and azobismethylbutyronitrile; and awell-known organic peroxide such as 2,4-diphenyl-4-methyl-1-pentene,benzoyl peroxide, t-butylperoxybenzoate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, t-butylperoxyisopropylmonocarbonate, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide,dicumyl peroxide, ethyl-3,3-di-(t-butylperoxy) butyrate, but notparticularly limited thereto. Only one type of the initiators may beused, or two or more types of the initiators may be used in combination.From the viewpoint of controlling reaction rate of the polymerizationand polymerization rate, it is preferable to use the azo compound or theorganic peroxide having a 10-hour half-life at 70 to 120° C. The amountof the polymerization initiators to be used is preferably 0.1 to 1.5parts by mass, more preferably 0.1 to 1.0 part by mass, based on 100parts by mass of all the monomers used for the polymerization, but notparticularly limited thereto. It is preferable that the amount of thepolymerization initiators to be used is 0.1 part by mass or more,because the polymerization rate becomes sufficient. When the amount ofthe polymerization initiators to be used is 1.5 parts by mass or less,the polymerization rate can be suppressed, so that the reaction can beeasily controlled, and the target molecular weight can be easilyobtained.

A chain transfer agent can be used for producing the maleimide-basedcopolymer. Examples of the chain transfer agents to be used includen-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan,α-methylstyrene dimer, ethyl thioglycolate, limonene, terpinolene, butnot particularly limited thereto. The amount of the chain transferagents to be used is preferably 0.01 to 0.8 parts by mass, morepreferably 0.1 to 0.5 parts by mass, based on 100 parts by mass of allmonomers used for the polymerization, as long as the target molecularweight can be obtained, but not particularly limited thereto. When theamount of the chain transfer agents to be used is 0.01 to 0.8 parts bymass, the target molecular weight can be easily obtained.

The maleimide-based copolymer of the present invention may be obtainedby copolymerizing the above-mentioned aromatic vinyl monomers, vinylcyanide monomers and unsaturated dicarboxylic anhydride monomers, andthen imidizing the unsaturated dicarboxylic anhydride monomer units inthe copolymer with ammonia or primary amine to convert them into themaleimide monomer units (a post-imidization method). It is preferable toobtain the maleimide-based copolymer by the post-imidization methodbecause the amount of the residual maleimide-based monomers in thecopolymer is reduced.

The primary amine includes: alkylamine such as methylamine, ethylamine,n-propylamine, iso-propylamine, n-butylamine, n-pentylamine,n-hexylamine, n-octylamine, cyclohexylamine and decylamine; and aromaticamine such as chlor- or bromo-substituted alkylamine, aniline, toluidinenaphthylamine, among which the aniline and the cyclohexylamine arepreferred. Only one type of the primary amines may be used, or two ormore types of the primary amines may be used in combination. The amountof the primary amines to be added is preferably 0.7 to 1.1 molarequivalents, more preferably 0.85 to 1.05 molar equivalents, based onthe unsaturated dicarboxylic anhydride monomer unit, but notparticularly limited thereto. It is preferable that the amount of theprimary amines to be added is 0.7 molar equivalent or more based on theunsaturated dicarboxylic acid anhydride monomer unit in themaleimide-based copolymer, because the thermal stability of the obtainedresin composition is improved. It is also preferable that the amount ofthe primary amines to be added is 1.1 molar equivalent or less, becausethe remaining amount of the primary amines in the maleimide-basedcopolymer is reduced.

When the maleimide-based copolymer is obtained by the post-imidizationmethod, a catalyst for improving a dehydration ring closure reaction canbe used in the reaction of the ammonia or the primary amine with theunsaturated dicarboxylic anhydride monomer unit, in particular, thereaction to convert the unsaturated dicarboxylic anhydride monomer unitto the maleimide monomer unit, as needed. The catalyst includes tertiaryamine such as trimethylamine, triethylamine, tripropylamine,tributylamine, N, N-dimethylaniline, and N, N-diethylaniline, but notparticularly limited thereto. The amount of the tertiary amines to beadded is preferably 0.01 mole equivalent or more based on theunsaturated dicarboxylic anhydride monomer unit, but not particularlylimited thereto. The temperature of the imidization reaction in thepresent invention is preferably 100 to 250° C., more preferably 120 to200° C. From the viewpoint of productivity, it is preferable that thetemperature of the imidation reaction is 100° C. or higher because thereaction rate become sufficiently high. It is preferable that thetemperature of the imidization reaction is 250° C. or lower, because adecrease in physical properties due to the thermal deterioration of themaleimide-based copolymer can be suppressed.

In the post-imidization method for obtaining the maleimide-basedcopolymer, it is also possible to carry out the polymerization in theinitial stage of the polymerization, using the total amount of thearomatic vinyl monomers, vinyl cyanide monomers and unsaturateddicarboxylic anhydride monomers to be added. However, the aromatic vinylmonomer and unsaturated dicarboxylic anhydride monomer have a strongtendency to copolymerize with each other. Therefore, the aromatic vinylmonomer and the unsaturated dicarboxylic anhydride monomer are consumedin the early stage of the polymerization, and a copolymer having a largeamount of the vinyl cyanide monomer units may be easily generated in thelate stage of the polymerization. As a result, the hue of the obtainedmaleimide-based copolymer may deteriorate and/or the physical propertyof the obtained resin composition may be unfavorable due to the widedistribution of the composition and the lack of the compatibility at thetime of mixing with the ABS resin or the like. Therefore, in order toobtain a (uniform) maleimide-based copolymer having a favorable hue anda narrow composition distribution, it is preferable to use a productionmethod having the following steps.

Initial polymerization step: A total amount of the vinyl cyanidemonomers to be added, 10 to 90% by mass of a total amount of thearomatic vinyl monomers to be added, and 0 to 30% by mass of a totalamount of the unsaturated dicarboxylic anhydride monomers to be addedare mixed to start copolymerization.

Middle polymerization step: 50 to 90% by mass of the remaining amount ofthe aromatic vinyl-based monomers used in the initial polymerizationstep, and the remaining amount of the unsaturated dicarboxylic anhydridemonomers used in the initial polymerization step are each separately orcontinuously added to the mixture to continue the copolymerization.

Final polymerization step: The remaining amount of the aromatic vinylmonomers used in the initial polymerization step and the middlepolymerization step is added to the mixture to obtain an aromaticvinyl-vinyl cyanide-unsaturated dicarboxylic anhydride copolymers.

Imidation step: The obtained aromatic vinyl-vinyl cyanide-unsaturateddicarboxylic anhydride copolymer is imidized with ammonia or primaryamine to obtain the maleimide-based copolymers.

As a means (devolatilization means) for removing volatile componentssuch as a solvent used for solution polymerization and unreactedmonomers from a solution after the solution polymerization of themaleimide-based copolymer or after the post-imidization, a well-knownmeans such as a vacuum devolatilization tank with a heater and adevolatilization extruder with a vent can be used. In a granulationstep, the devolatilized maleimide-based copolymers in molten state canbe extruded into a strand-shaped copolymer from a porous die and then beprocessed into pellet shapes by a cold cut method, an air hot cutmethod, or an underwater hot cut method.

The obtained maleimide-based copolymers can be used as a heat resistanceimparting agent for a resin composition obtained by mixing with variousresins. The resin includes the ABS resin, ASA resin, AES resin, and SANresin, but not particularly limited thereto. Since these resins have anexcellent compatibility with the maleimide-based copolymer, a highheat-resistance can be imparted to the obtained resin composition. Theblending ratio of the maleimide-based copolymer and the resin ispreferably 5 to 40% by mass of the maleimide-based copolymer and 60 to95% by mass of one or more selected from the group consisting of the ABSresin, ASA resin, AES resin and SAN resin, more preferably 10 to 30% bymass of the maleimide-based copolymer and 70 to 90% by mass of one ormore resins selected from the group consisting of the ABS resin, ASAresin, AES resin and SAN resin.

When the blending ratio of the maleimide-based copolymer is in thisrange, the effect of improving the heat resistance of the resincomposition is obtained, and the chemical resistance and hue of theresin composition are not reduced.

As a technique for mixing the maleimide-based copolymer with one or moreresins, a well-known melt-mixing technique can be used, but notparticularly limited thereto. A suitable melt-mixing apparatus include:a screw extruder such as a single-screw extruder, a fully meshingco-rotating twin-screw extruder, a fully meshing different-directiontwin-screw extruder, and a non- or incompletely meshing twin-screwextruder; a ban bury mixer; a co-kneader; and mixing roll.

In the mixing of the maleimide-based copolymer with one or more resins,a stabilizer, an ultraviolet absorber, a flame retardant, a plasticizer,a lubricant, a glass fiber, an inorganic filler, a coloring agent, anantistatic agent, and the like can be further added.

In order to obtain a molded article from the resin composition,well-known molding techniques such as an injection molding, an extrusionmolding, a sheet molding and a press molding can be used. The resincomposition of the present invention is particularly excellent in theheat resistance and can be particularly used suitably as a material forinjection molding which is subjected to high temperature and highpressure during the molding.

The molded article obtained by molding the resin composition can besuitably used for an interior member or an exterior member of anautomobile.

EXAMPLES

Hereinafter, detailed contents will be described using examples, but thepresent invention is not limited to the following examples.

Production Example of Maleimide-Based Copolymer (A-1)

22 parts by mass of styrene, 13 parts by mass of acrylonitrile, 4 partsby mass of maleic anhydride, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 12 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 28 parts by mass ofstyrene and a solution prepared by dissolving 25 parts by mass of maleicanhydride and 0.22 parts by mass of t-butylperoxy-2-ethylhexanoate in 75parts by mass of methyl ethyl ketone were continuously added over 7hours. After completion of the addition of the maleic anhydride, 8 partsby mass of the styrene was continuously added over 2 hours. After theaddition of the styrene, the temperature was raised to 120° C. Thereaction was carried out for 1 hour. After completion of the reaction,the polymerization was completed. Thereafter, 26 parts by mass ofaniline and 0.5 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 140° C. for 7 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-1 in a pellet form. Table 1 shows the analysis results of the obtainedmaleimide-based copolymer A-1.

Production Example of Maleimide-Based Copolymer (A-2)

20 parts by mass of styrene, 8 parts by mass of acrylonitrile, 4 partsby mass of N-phenylmaleimide, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 16 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 23 parts by mass ofstyrene and a solution prepared by dissolving 38 parts by mass ofN-phenylmaleimide and 0.2 parts by mass oft-butylperoxy-2-ethylhexanoate in 152 parts by mass of methyl ethylketone were continuously added over 7 hours. After completion of theaddition of the N-phenylmaleimide, 7 parts by mass of the styrene wascontinuously added over 2 hours. After the addition of the styrene, thetemperature was raised to 120° C. The reaction was carried out for 1hour. After completion of the reaction, the polymerization wascompleted. After completion of the reaction, the polymerization solutionwas added into the vent-type screw extruder. Volatile components wereremoved to obtain a maleimide-based copolymer A-2 in a pellet form.Table 1 shows the analysis results of the obtained maleimide-basedcopolymer A-2.

Production Example of Maleimide-Based Copolymer (A-3)

17 parts by mass of styrene, 22 parts by mass of acrylonitrile, 5 partsby mass of maleic anhydride, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 20 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 28 parts by mass ofstyrene and a solution prepared by dissolving 20 parts by mass of maleicanhydride and 0.25 parts by mass of t-butylperoxy-2-ethylhexanoate in 80parts by mass of methyl ethyl ketone were continuously added over 7hours. After completion of the addition of the maleic anhydride, 8 partsby mass of the styrene was continuously added over 2 hours. After theaddition of the styrene, the temperature was raised to 120° C. Thereaction was carried out for 1 hour. After completion of the reaction,the polymerization was completed. Thereafter, 22 parts by mass ofaniline and 0.4 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 140° C. for 7 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-3 in a pellet form. Table 1 shows the analysis results of the obtainedmaleimide-based copolymer A-3.

Production Example of Maleimide-Based Copolymer (A-4)

13 parts by mass of styrene, 11 parts by mass of acrylonitrile, 6 partsby mass of maleic anhydride, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 18 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 31 parts by mass ofstyrene and a solution prepared by dissolving 30 parts by mass of maleicanhydride and 0.2 parts by mass of t-butylperoxy-2-ethylhexanoate in 90parts by mass of methyl ethyl ketone were continuously added over 7hours. After completion of the addition of the maleic anhydride, 9 partsby mass of the styrene was continuously added over 2 hours. After theaddition of the styrene, the temperature was raised to 120° C. Thereaction was carried out for 1 hour. After completion of the reaction,the polymerization was completed. Thereafter, 32 parts by mass ofaniline and 0.6 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 140° C. for 7 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-4 in a pellet form. Table 1 shows the analysis results of the obtainedmaleimide-based copolymer A-4.

Production Example of Maleimide-Based Copolymer (A-5)

45 parts by mass of styrene, 8 parts by mass of acrylonitrile, 0.1 partby mass of 2,4-diphenyl-4-methyl-1-pentene, 16 parts by mass of methylethyl ketone were added into about 120-liter autoclave equipped with astirrer, and then heated to 92° C. over 40 minutes while stirring afterreplacing a gas phase in the autoclave with nitrogen gas. Whilemaintaining the temperature at 92° C. after the temperature rise, 18parts by mass of styrene and a solution prepared by dissolving 24 partsby mass of maleic anhydride and 0.3 parts by mass oft-butylperoxy-2-ethylhexanoate in 96 parts by mass of methyl ethylketone were continuously added over 7 hours. After completion of theaddition of the maleic anhydride, 5 parts by mass of the styrene wascontinuously added over 2 hours. After the addition of the styrene, thetemperature was raised to 120° C. The reaction was carried out for 1hour. After completion of the reaction, the polymerization wascompleted. Thereafter, 21 parts by mass of aniline and 0.4 parts by massof triethylamine were added to the polymerization solution. After theaddition, the reaction was carried out at 140° C. for 7 hours. Aftercompletion of the reaction, the imidization reaction solution was addedinto a vent-type screw extruder. Volatile components were removed toobtain a maleimide-based copolymer A-5 in a pellet form. Table 1 showsthe analysis results of the obtained maleimide-based copolymer A-5.

Production Example of Maleimide-Based Copolymer (A-6)

22 parts by mass of styrene, 13 parts by mass of acrylonitrile, 4 partsby mass of maleic anhydride, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 12 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 32 parts by mass ofstyrene and a solution prepared by dissolving 25 parts by mass of maleicanhydride and 0.22 parts by mass of t-butylperoxy-2-ethylhexanoate in 75parts by mass of methyl ethyl ketone were continuously added over 8hours. After completion of the addition of the maleic anhydride, 4 partsby mass of the styrene was continuously added over 1 hour. After theaddition of the styrene, the temperature was raised to 120° C. Thereaction was carried out for 1 hour. After completion of the reaction,the polymerization was completed. Thereafter, 26 parts by mass ofaniline and 0.5 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 140° C. for 7 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-6 in a pellet form. Table 1 shows the analysis results of the obtainedmaleimide-based copolymer A-6.

Production Example of Maleimide-Based Copolymer (A-7)

59.7 parts by mass of styrene, 3.8 parts by mass of acrylonitrile, 0.05part by mass of 2,4-diphenyl-4-methyl-1-pentene, 18 parts by mass ofmethyl isobutyl ketone were added into about 120-liter autoclaveequipped with a stirrer, and then heated to 90° C. over 40 minutes whilestirring after replacing a gas phase in the autoclave with nitrogen gas.While maintaining the temperature at 90° C. after the temperature rise,a solution prepared by dissolving 36.5 parts by mass of maleic anhydrideand 0.1 part by mass of t-butylperoxy-2-ethylhexanoate in 120 parts bymass of methyl isobutyl ketone were continuously added over 4 hours.After completion of the addition of the maleic anhydride, thetemperature was raised to 110° C. The reaction was carried out for 2hours. After completion of the reaction, the polymerization wascompleted. Thereafter, 32.7 parts by mass of aniline and 0.5 parts bymass of triethylamine were added to the polymerization solution. Afterthe addition, the reaction was carried out at 155° C. for 4 hours. Aftercompletion of the reaction, the imidization reaction solution was addedinto a vent-type screw extruder. Volatile components were removed toobtain a maleimide-based copolymer A-7 in a pellet form. Table 2 showsthe analysis results of the obtained maleimide-based copolymer A-7.

Production Example of Maleimide-Based Copolymer (A-8)

25.1 parts by mass of styrene, 14.9 parts by mass of acrylonitrile, 0.05part by mass of 2,4-diphenyl-4-methyl-1-pentene, 18 parts by mass ofmethyl isobutyl ketone were added into about 120-liter autoclaveequipped with a stirrer, and then heated to 90° C. over 40 minutes whilestirring after replacing a gas phase in the autoclave with nitrogen gas.While maintaining the temperature at 90° C. after the temperature rise,25 parts by mass of styrene and a solution prepared by dissolving 35parts by mass of maleic anhydride and 0.1 part by mass oft-butylperoxy-2-ethylhexanoate in 120 parts by mass of methyl isobutylketone were continuously added over 4 hours. After completion of theaddition of the maleic anhydride, the temperature was raised to 110° C.The reaction was carried out for 2 hours. After completion of thereaction, the polymerization was completed. Thereafter, 31.9 parts bymass of aniline and 0.5 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 155° C. for 4 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-8 in a pellet form. Table 2 shows the analysis results of the obtainedmaleimide-based copolymer A-8.

Production Example of Maleimide-Based Copolymer (A-9)

65 parts by mass of styrene, 8 parts by mass of acrylonitrile, 2 partsby mass of maleic anhydride, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 10 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 7 parts by mass ofstyrene and a solution prepared by dissolving 16 parts by mass of maleicanhydride and 0.3 parts by mass of t-butylperoxy-2-ethylhexanoate in 80parts by mass of methyl ethyl ketone were continuously added over 7hours. After completion of the addition of the maleic anhydride, 2 partsby mass of the styrene was continuously added over 2 hours. After theaddition of the styrene, the temperature was raised to 120° C. Thereaction was carried out for 1 hour. After completion of the reaction,the polymerization was completed. Thereafter, 16 parts by mass ofaniline and 0.3 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 140° C. for 7 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-9 in a pellet form. Table 2 shows the analysis results of the obtainedmaleimide-based copolymer A-9.

Production Example of Maleimide-Based Copolymer (A-10)

14 parts by mass of styrene, 28 parts by mass of acrylonitrile, 3 partsby mass of maleic anhydride, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 12 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 25 parts by mass ofstyrene and a solution prepared by dissolving 23 parts by mass of maleicanhydride and 0.4 parts by mass of t-butylperoxy-2-ethylhexanoate in 92parts by mass of methyl ethyl ketone were continuously added over 7hours. After completion of the addition of the maleic anhydride, 7 partsby mass of the styrene was continuously added over 2 hours. After theaddition of the styrene, the temperature was raised to 120° C. Thereaction was carried out for 1 hour. After completion of the reaction,the polymerization was completed. Thereafter, 23 parts by mass ofaniline and 0.4 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 140° C. for 7 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-10 in a pellet form. Table 2 shows the analysis results of theobtained maleimide-based copolymer A-10.

Production Example of Maleimide-Based Copolymer (A-11)

2 parts by mass of styrene, 10 parts by mass of acrylonitrile, 5 partsby mass of maleic anhydride, 0.1 part by mass of2,4-diphenyl-4-methyl-1-pentene, 15 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. over 40 minutes while stirring after replacing agas phase in the autoclave with nitrogen gas. While maintaining thetemperature at 92° C. after the temperature rise, 35 parts by mass ofstyrene and a solution prepared by dissolving 38 parts by mass of maleicanhydride and 0.4 parts by mass of t-butylperoxy-2-ethylhexanoate in 114parts by mass of methyl ethyl ketone were continuously added over 7hours. After completion of the addition of the maleic anhydride, 10parts by mass of the styrene was continuously added over 2 hours. Afterthe addition of the styrene, the temperature was raised to 120° C. Thereaction was carried out for 1 hour. After completion of the reaction,the polymerization was completed. Thereafter, 38 parts by mass ofaniline and 0.7 parts by mass of triethylamine were added to thepolymerization solution. After the addition, the reaction was carriedout at 140° C. for 7 hours. After completion of the reaction, theimidization reaction solution was added into a vent-type screw extruder.Volatile components were removed to obtain a maleimide-based copolymerA-11 in a pellet form. Table 2 shows the analysis results of theobtained maleimide-based copolymer A-11.

Production Example of Maleimide-Based Copolymer (A-12)

65 parts by mass of styrene, 7 parts by mass of maleic anhydride, 0.2parts by mass of 2,4-diphenyl-4-methyl-1-pentene, 25 parts by mass ofmethyl ethyl ketone were added into about 120-liter autoclave equippedwith a stirrer, and then heated to 92° C. after replacing a gas phase inthe autoclave with nitrogen gas. A solution prepared by dissolving 28parts by mass of maleic anhydride and 0.18 parts by mass oft-butylperoxy-2-ethylhexanoate in 100 parts by mass of methyl ethylketone were continuously added over 7 hours. After the addition, 0.03parts by mass of the t-butylperoxy-2-ethylhexanoate was further added.After the addition of t-butylperoxy-2-ethylhexanoate, the temperaturewas raised to 120° C. The reaction was carried out for 1 hour. Aftercompletion of the reaction, the polymerization was completed.Thereafter, 32 parts by mass of aniline and 0.6 parts by mass oftriethylamine were added to the polymerization solution. After theaddition, the reaction was carried out at 140° C. for 7 hours. Aftercompletion of the reaction, the imidization reaction solution was addedinto a vent-type screw extruder. Volatile components were removed toobtain a maleimide-based copolymer A-12 in a pellet form. Table 2 showsthe analysis results of the obtained maleimide-based copolymer A-12.

Production Example of Maleimide-Based Copolymer (A-13)

40 parts by mass of styrene, 16 parts by mass of acrylonitrile, 5 partsby mass of maleic anhydride, 0.2 parts by mass of2,4-diphenyl-4-methyl-1-pentene, 20 parts by mass of methyl ethyl ketonewere added into about 120-liter autoclave equipped with a stirrer, andthen heated to 92° C. after replacing a gas phase in the autoclave withnitrogen gas. 18 parts by mass of styrene and a solution prepared bydissolving 16 parts by mass of maleic anhydride and 0.3 parts by mass oft-butylperoxy-2-ethylhexanoate in 80 parts by mass of methyl ethylketone were continuously added over 7 hours. After completion of theaddition of the maleic anhydride, 5 parts by mass of the styrene wascontinuously added over 2 hours. After the addition of the styrene, thetemperature was raised to 120° C. The reaction was carried out for 1hour. After completion of the reaction, the polymerization wascompleted. Thereafter, 19 parts by mass of aniline and 0.4 parts by massof triethylamine were added to the polymerization solution. After theaddition, the reaction was carried out at 140° C. for 7 hours. Aftercompletion of the reaction, the imidization reaction solution was addedinto a vent-type screw extruder. Volatile components were removed toobtain a maleimide-based copolymer A-13 in a pellet form. Table 2 showsthe analysis results of the obtained maleimide-based copolymer A-13.

TABLE 1 Exam. 1 Exam. 2 Exam. 3 Exam. 4 Exam. 5 Exam. 6 A-1 A-2 A-3 A-4A-5 A-6 Structure Aromatic vinyl monomer unit % by mass 47.2 51.0 45.242.0 56.3 47.3 unit Vinyl cyanide monomer unit % by mass 10.2 8.0 17.57.9 6.5 10.3 Maleimide monomer unit % by mass 41.2 41.0 36.0 18.6 35.941.0 Unsaturated dicarboxylic % by mass 1.4 — 1.3 1.5 1.3 1.4 anhydridemonomer unit Transmittance at 450 nm 93 93 91 90 94 91 Glass transitiontemperature ° C. 175 173 167 195 166 175 Amount of residual ppm 150 180120 260 120 250 maleimide monomer

TABLE 2 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Exam. 1 Exam. 2 Exam.3 Exam. 4 Exam. 5 Exam. 6 Exam. 7 A-7 A-8 A-9 A-10 A-11 A-12 A-13Structure Aromatic vinyl monomer unit % by mass 47.21 3S.8 65.6 38.937.3 51.1 53.6 unit Vinyl cyanide monomer unit % by mass 3.0 11.9 7.122.9 7.3 — 14.2 Maleimide monomer unit % by mass 48.0 47.2 26.4 36.953.7 48.1 31.2 Unsaturated dicarboxylic % by mass 1.7 1.1 0.9 1.3 1.70.8 1.0 anhydride monomer unit Transmittance at 450 nm % 89 82 94 79 8595 92 Glass transition temperature ° C. 164 142 140 160 183 188 149Amount of residual ppm 210 230 150 190 450 170 170 maleimide monomer

Composition Analysis

The maleimide-based copolymers were measured by C-13 NMR method underthe following measurement conditions.

Apparatus name: FT-NMR AVANCE300 (manufactured by BRUKER)

Solvent: Deuterated chloroform

Concentration: 14% by mass

Temperature: 27° C.

Number of scans: 8000 times

Transmittance at 450 nm

Each maleimide-based copolymer was dissolved in tetrahydrofuran toprepare a tetrahydrofuran solution containing 4% by mass of thecopolymer. After filling each solution into a quartz square cell with ameasuring optical path length of 10 mm, the transmittance of eachsolution was measured using a spectrophotometer V-670ST (manufactured byJASCO Corporation).

Glass Transition Temperature

An extrapolated glass transition initiation temperature (Tig) of eachmaleimide-based copolymer was measured according to JIS K-7121 using thefollowing apparatus and measuring conditions.

Apparatus name: Robot DSC6200 (manufactured by Seiko Instruments Inc.)

Heating rate: 10° C./min

Amount of Residual Maleimide Monomer

Procedure: 0.5 g of a sample is dissolved in 5 ml of a1,2-dichloroethane solution (0.014 g/L) containing undecane (internalstandard). Thereafter, 5 ml of n-hexane is added and shaken for 10 to 15minutes with a shaker to precipitate polymers. With the polymerprecipitated, only the supernatant is injected into the gaschromatograph. A quantitative value was calculated from the peak area ofthe obtained maleimide-based monomer using a coefficient obtained froman internal standard substance.

Apparatus name: Gas Chromatograph GC-2010 (manufactured by ShimadzuCorporation)

Column: Capillary column DB-5 ms (manufactured by Agilent TechnologyCo., Ltd.)

Temperature: Inlet temperature of 280° C., detector temperature of 280°C.

-   -   Perform a temperature rise analysis at a column temperature of        80° C. (initial).

(Temperature rising analysis conditions) 80° C.: constant for 12 minutes

-   -   80-280° C.: 10 min at 20° C./min    -   280° C.: constant for 10 minutes

Detector: FID

Resin Composition Examples 7 to 14 (Exam. 7 to 14) and ComparativeExamples 8 to 16 (Comp. Exam. 8 to 16) (Mixing of Maleimide-BasedCopolymer and ABS Resin)

Each of the maleimide-based copolymers A-1 to A-13 was blended with acommercially available ABS resin GR-3000 (manufactured by DenkaCorporation) at the blending ratio (% by mass) shown in Tables 3 and 4.After the blending, the mixture was extruded and pelletized using a twinscrew extruder TEM-35B (manufactured by Toshiba Machine Co., Ltd.) underthe conditions shown in Tables 3 and 4. Using the pellets, test pieceswere prepared by an injection molding machine, and each physicalproperty value was measured. The results are shown in Tables 3 and 4.

TABLE 3 Exam. Exam. Exam. Exam. Exam. Exam. Exam. Exam. 7 8 9 10 11 1213 14 Blending Maleimide-based copolymer A-1 15 8 35 — — — — ratioMaleimide-based copolymer A-2 — — — 15 — — — — Maleimide-based copolymerA-3 — — — — 15 — — — Maleimide-based copolymer A-4 — — — — — 15 — —Maleimide-based copolymer A-5 — — — — — — 15 — Maleimide-based copolymerA-6 — — — — — — — 15 ABS resin (GR-3000) 85 92 65 85 85 85 85 85 Charpyimpact strength kJ/m² 24 28 18 25 26 21 25 25 Melt mass flow rate g/10min 8 16 3 6 10 5 13 7 Vicat softening point ° C. 115 110 125 115 113118 112 115 Chemical resistance — Great Great Fair Good Great Good FairGreat YI — 30 28 38 30 34 36 29 35

TABLE 4 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Exam.Exam. Exam. Exam. Exam. Exam. Exam. Exam. Exam. 8 9 10 11 12 13 14 15 16Blending Maleimide-based copolymer A-1 3 50 — — — — — — — ratioMaleimide-based copolymer A-7 — — 15 — — — — — — Maleimide-basedcopolymer A-8 — — — 15 — — — — — Maleimide-based copolymer A-9 — — — —15 — — — — Maleimide-based copolymer A-10 — — — — — 15 — — —Maleimide-based copolymer A-11 — — — — — — 15 — — Maleimide-basedcopolymer A-12 — — — — — — — 15 — Maleimide-based copolymer A-13 — — — —— — — — 15 ABS resin (GR-3000) 97 50 85 85 85 85 85 85 85 Charpy impactstrength kJ/m² 29 12 19 21 22 24 17 19 21 Melt mass flow rate g/10 min27 1 6 5 19 10 4 5 15 Vicat softening point ° C. 103 132 118 118 108 113119 117 109 Chemical resistance — Great Poor Poor Good Fair Great FairPoor Good YI — 26 45 41 48 25 55 45 28 35

Charpy Impact Strength

According to JIS K-7111, the Charpy impact strength was measured using anotched test piece under relative humidity of 50% and ambienttemperature of 23° C. The impact direction was edgewise. The measuringdevice used was a digital impact tester (manufactured by Toyo SeikiSeisaku-sho, Ltd.). The case where the Charpy impact strength was 15kJ/m² or more was judged to be good.

Melt Mass Flow Rate

According to JIS K7210, the melt mass flow rate was measured at 220° C.under a load of 98 N. The case where the melt mass flow rate was 3 g/10minutes or more was judged to be good.

Vicat Softening Point

According to JIS K7206, the Vicat softening point was measured by a 50method (load of 50 N, heating rate of 50° C./hour) using a test piecehaving a length of 10 mm, a width of 10 mm and a thickness of 4 mm. Ameasuring device used was an HDT & VSPT test device (manufactured byToyo Seiki Seisaku-sho, Ltd.). The case where the Vicat softening pointwas 110° C. or higher was judged to be good.

Chemical Resistance

Cracks of a test piece having a shape of 316×20×2 mm were observed after48 hours at 23° C. by a quarter ellipse method having a major radius of250 mm and a minor radius of 150 mm. In order to eliminate influence ofmolding strain, the test piece was produced by pressing and cutting outa pellet at 260° C. Toluene is used as the chemical.

Critical strain was calculated by the following equation.

ε=b/2a ²[1-(a ² −b ²)X ² /a ⁴]^(1.5) *t*100

Critical strain: ε, major radius: a, minor radius: b, thickness of testpiece: t, crack initiation point: X

The chemical resistance was evaluated from the critical strain accordingto the following criteria.

Great: 0.8 or more, Good: 0.6 to 0.7, Fair: 0.3 to 0.5, Poor: 0.2 orless

YI (hue)

A plate (9 cm×5 cm) was molded at a molding temperature of 240° C. usingan injection molding machine IS-50EP (manufactured by Toshiba MachineCo., Ltd.). The yellowness YI of the molded plate was measured by acolor difference meter COLOR-7e² (manufactured by Kurashiki SpinningCo., Ltd.). The case where the yellowness YI was 40 or less was judgedto be good.

The maleimide-based copolymers of Examples 1 to 6 (Exam. 1 to 6) of thepresent invention had a sufficiently high transmittance at 450 nm and asufficiently high glass transition temperature. Therefore, the resincompositions of Examples 7 to 14 (Exam. 7 to 14) in which themaleimide-based copolymer and the ABS resin were mixed were excellent inthe impact resistance, fluidity, heat resistance, chemical resistance,and hue. The matrix resin of the ABS resin is an AS resin. Thus, whenthe maleimide-based copolymer of the present invention is mixed with theAS resin or an AES resin or an ASA resin using the AS resin as a matrixresin, it is expected that the same effects as those shown in theexamples can be exerted. On the other hand, the maleimide-basedcopolymers of Comparative Examples 1 to 7 (Comp. Exam. 1 to 7) were outof the scope of the present invention. The resin compositions ofComparative Examples 8 to 16 (Comp. Exam. 8 to 16) in which themaleimide-based copolymer and the ABS resin were mixed were inferior inany of the impact resistance, fluidity, heat resistance, chemicalresistance, and hue.

INDUSTRIAL APPLICABILITY

A resin composition having an excellent balance of physical propertiesfor the hue, chemical resistance, heat resistance, impact resistance,and fluidity by mixing the maleimide-based copolymer of the presentinvention with the ABS resin, the ASA resin, the AES resin or the SANresin can be obtained. The obtained resin composition can be suitablyused as a material for an interior member or an exterior member of anautomobile.

1. A maleimide-based copolymer comprising 40 to 60% by mass of an aromatic vinyl monomer units, 5 to 20% by mass of a vinyl cyanide monomer units, and 35 to 50% by mass of a maleimide-based monomer units, wherein a tetrahydrofuran solution containing 4% by mass of the copolymers has a transmittance of 90% or more for light having a wavelength of 450 nm at an optical path length of 10 mm, and an amount of the residual maleimide-based monomers is less than 300 ppm.
 2. The maleimide-based copolymer according to claim 1, further comprising 0 to 10% by mass of unsaturated dicarboxylic anhydride monomer units in the maleimide-based copolymer.
 3. The maleimide-based copolymer according to claim 1, comprising a glass transition temperature of 165° C. or higher.
 4. A method for producing the maleimide-based copolymer according to claim 1, comprising an initial polymerization step, a middle polymerization step, a final polymerization step and an imidization step, where in the initial polymerization step, a total amount of vinyl cyanide monomers to be added, 10 to 90% by mass of a total amount of aromatic vinyl monomers to be added, and 0 to 30% by mass of a total amount of unsaturated dicarboxylic anhydride monomers to be added are mixed to start copolymerization, in the middle polymerization step, 50 to 90% by mass of the remaining amount of the aromatic vinyl monomers used in the initial polymerization step and the remaining amount of the unsaturated dicarboxylic anhydride monomers used in the initial polymerization step are each separately or continuously added to the mixture to continue the copolymerization, in the final polymerization step, the remaining amount of the aromatic vinyl monomers used in the initial polymerization step and the middle polymerization step is added to the mixture to obtain aromatic vinyl-vinyl cyanide-unsaturated dicarboxylic anhydride copolymers, and in the imidization step, the obtained aromatic vinyl-vinyl cyanide-unsaturated dicarboxylic anhydride copolymers are imidized with ammonia or primary amine to obtain the maleimide-based copolymers.
 5. A resin composition comprising 5 to 40% by mass of the maleimide-based copolymer according to claim 1, and 60 to 95% by mass of one or more resins selected from an acrylonitrile-butadiene-styrene copolymer resin (ABS resin), an acrylonitrile-styrene-acrylate-based rubber copolymer resin (ASA resin), an acrylonitrile-ethylene propylene-based rubber-styrene copolymer resin (AES resin) and a styrene-acrylonitrile copolymer resin (SAN resin).
 6. An injection molded article using the resin composition according to claim
 5. 7. The injection molded article according to claim 6, used as an interior member or an exterior member of an automobile. 